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Qiang Zhao, Zhen Lian, Xuedong Gao, Yun Yan, Jianbin Huang
The ability to modulate the amphiphilic aggregation reversibly with external stimuli, especially by light trigger, is of great importance. It makes great contribution to the development of applications by self-assembly. However, most previously described systems are based on specific molecular design and difficultly applied in light-inert aggregations. Here we develop a general and effective approach to control the morphology of amphiphilic aggregates by light, which is suitable for different assemblies such as micelle, vesicle and helix...
October 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Claire E Weston, Andreas Kraemer, Felix Colin, Özkan Yildiz, Matthias G J Baud, Franz-Josef Meyer-Almes, Matthew J Fuchter
Photopharmacological agents exhibit light-dependent biological activity and may have potential in the development of new antimicrobial agents/modalities. Amidohydrolase enzymes homologous to the well known human histone deacetylases (HDACs) are present in bacteria, including resistant organisms responsible for a significant number of hospital acquired infections and deaths. We report photopharmacological inhibitors of these enzymes, using two classes of photoswitch embedded in the inhibitor pharmacophore: azobenzenes and arylazopyrazoles...
October 18, 2016: ACS Infectious Diseases
Rayya A Al-Balushi, Ashanul Haque, Maharaja Jayapal, Mohammed K Al-Suti, John Husband, Muhammad S Khan, Jonathan M Skelton, Kieran C Molloy, Paul R Raithby
Trimethylsilyl-protected dialkynes incorporating azobenzene linker groups, Me3SiC≡CRC≡CSiMe3 (R = azobenzene-3,3'-diyl, azobenzene-4,4'-diyl, 2,5-dioctylazobenzene-4,4'-diyl), and the corresponding terminal dialkynes, HC≡CRC≡CH, have been synthesized and characterized. The CuI-catalyzed dehydrohalogenation reaction between trans-[Ph(Et3P)2PtCl] and the deprotected dialkynes in a 2:1 ratio in (i)Pr2NH/CH2Cl2 gives the platinum(II) diynes trans-[Ph(Et3P)2PtC≡CRC≡CPt(PEt3)2Ph], while the dehydrohalogenation polycondensation reaction between trans-[((n)Bu3P)2PtCl2] and the dialkynes in a 1:1 molar ratio under similar reaction conditions affords the platinum(II) polyynes, [-Pt(P(n)Bu3)2-C≡CRC≡C-]n...
October 18, 2016: Inorganic Chemistry
Yong Li, Xu Wang, Jie Yang, Xilei Xie, Mengmeng Li, Jinye Niu, Lili Tong, Bo Tang
Carbon monoxide (CO), a crucial gas message molecule, plays an important role in the regulation of physiological and pathological process. Hypoxia-induced CO is involved in modulating various cellular activities, including signal transduction, proliferation, and apoptosis. However, tracking CO fluctuation in the hypoxic cells is still a challenge due to lack of straight forward, visualized and non-invasive tools. In this work, based on metal palladium-catalyzed reaction, we present the rational design, synthesis and biological utility of an azobenzene-cyclopalladium-based fluorescent probe, ACP-2, for CO monitoring...
October 17, 2016: Analytical Chemistry
Fan Xie, Long Qin, Minghua Liu
A novel amphiphilic dendron (AZOC8GAc) with three L-glutamic acid units and an azobenzene moiety covalently linked by an alkyl spacer was designed. The compound formed hydrogels with water in very low concentration and self-assembled into chiral twist structures. The gel showed a reversible macroscopic volume phase transition responding to pH variations and photo-irradiation. During the photo-triggered changes, although the gel showed a complete reversibility in their optical absorptions, only an incomplete chiroptical property was reached...
October 11, 2016: Chemistry: a European Journal
Yuki Kawata, Takahiro Yamamoto, Hideyuki Kihara, Yasuhisa Yamamura, Kazuya Saito, Kohji Ohno
Colloidal composites consisting of polymer-brush-afforded silica particles (P-SiPs) and a nematic liquid crystal (LC) exhibited three gel states with distinct viscoelastic and/or optical properties depending on temperature: (1) opaque hard gel, (2) translucent hard gel, and (3) translucent soft gel. We demonstrated that the transitions of the optical property and the hardness of the gels were due to the phase transition of the LC matrix and the glass transition of the grafted polymers of P-SiPs, respectively...
October 11, 2016: ACS Applied Materials & Interfaces
Wei-Chao Song, Xun-Zhe Cui, Zhong-Yi Liu, En-Cui Yang, Xiao-Jun Zhao
A self-catenated Zn(II)-organic framework formulated as [Zn2(3,3'-bpeab)(oba)2]·DMF (1) exhibiting a six-connected 4(4)·6(10)·8 topology has been successfully synthesized through the mixed-ligand of kinked 3,3'-bis[2-(4-pyridyl)ethenyl]azobenzene (3,3'-bpeab) and 4,4'-oxybis-benzoic acid (H2oba) under solvothermal condition. UV light triggers isomerization of complex 1 in a single-crystal-to-single-crystal (SCSC) manner, giving rise to a conformational supramolecular isomer 1_UV through the pedal motion of photoresponsive double bonds...
October 11, 2016: Scientific Reports
Selina Schimka, Nino Lomadze, Maren Rabe, Alexey Kopyshev, Maren Lehmann, Regine von Klitzing, Artem M Rumyantsev, Elena Yu Kramarenko, Svetlana Santer
We report on light sensitive microgel particles that can change their volume reversibly in response to illumination with light of different wavelengths. To make the anionic microgels photosensitive we add surfactants with a positively charged polyamine head group and an azobenzene containing tail. Upon illumination, azobenzene undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. Depending on the isomerization state, the surfactant molecules are either accommodated within the microgel (trans-state) resulting in its shrinkage or desorbed back into water (cis-isomer) letting the microgel swell...
October 10, 2016: Physical Chemistry Chemical Physics: PCCP
Jonas Kind, Lukas Kaltschnee, Martin Leyendecker, Christina M Thiele
Photochromic compounds like azobenzenes are widely used for the production of stimuli responsive materials. To analyse cascaded azobenzene switching inside a benzene-tricarboxamide (BTA) with three azobenzene moieties in a site-specific fashion, we used in situ irradiation NMR spectroscopy. Four photoisomers can be distinguished by their chemical shifts. Analysis of (1)H, (13)C and (15)N shifts reveals that the configuration of one sidechain has an influence on the chemical shifts of both the other sidechains...
October 13, 2016: Chemical Communications: Chem Comm
Héctor Barbero, Sergio Ferrero, Lucía Álvarez-Miguel, Patricia Gómez-Iglesias, Daniel Miguel, Celedonio M Álvarez
Six azobenzene derivatives bearing polyaromatic fragments have been prepared and their reversible photoisomerization has been assessed. Corannulene-functionalized molecules have demonstrated excellent switchable hosting abilities towards fullerenes in which an interesting range of affinities has been found. The success of this design relies upon the reversible formation and destruction of tweezer-like structures.
September 20, 2016: Chemical Communications: Chem Comm
Nadia Kapernaum, Carsten Müller, Svenja Moors, M Christian Schlick, Eugen Wuckert, Sabine Laschat, Frank Gießelmann
In ionic liquid crystals the orthogonal smectic A phase is the most common phase while the tilted smectic C phase is rather rare. We now present a new study with five novel ionic liquid crystals exhibiting both a smectic A as well as the rare smectic C phase. Two of them have a phenylpyrimidine core while the other three are imidazolium azobenzenes. Their phase sequences and tilt angles were studied by polarizing microscopy and their temperature dependent layer spacing as well as their translational and orientational order parameters were studied by X-ray diffraction...
October 6, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Jing Zhu, Peng Tan, Piao-Ping Yang, Xiao-Qin Liu, Yao Jiang, Lin-Bing Sun
Traditional adsorbents with fixed pore surface properties are unlikely to achieve both selective adsorption and efficient desorption, which are extremely desirable in adsorption processes. Here we report a new class of smart adsorbents by introducing photo-responsive azobenzene derivatives to pore interiors of mesoporous silica. The azobenzene molecules are applied as ON-OFF switches for active sites, and are reversibly regulated by UV/visible light irradiation, thus endowing the adsorbents with unprecedented properties to achieve selective adsorption and efficient desorption...
September 20, 2016: Chemical Communications: Chem Comm
Dae-Yoon Kim, Dong-Gue Kang, Myong-Hoon Lee, Jin-Soo Kim, Cheul-Ro Lee, Kwang-Un Jeong
A palladium(ii)-based metallomesogen with azobenzene was synthesized for the fabrication of an optically and electrically tunable polarized light modulator. Owing to the extended molecular geometry constructed by organometallic chemistry, the photo-responsive metallomesogen showed an excellent orientation in liquid crystal media.
October 3, 2016: Chemical Communications: Chem Comm
Andrea Monas, Krunoslav Užarević, Ivan Halasz, Marina Juribašić Kulcsár, Manda Ćurić
Room-temperature accelerated aging in the solid state has been applied for atom- and energy-efficient activation of either one or two C-H bonds of azobenzene and methyl orange by palladium(ii) acetate. Organopalladium complexes are prepared in quantitative reactions without potentially harmful side products. Dicyclopalladated methyl orange is water-soluble and is a selective chromogenic biothiol sensor at physiologically-relevant micromolar concentrations in buffered aqueous media.
September 9, 2016: Chemical Communications: Chem Comm
Xinran Zhou, Shouping Chen, Bingyang Liu, Xiaogong Wang
We report the successful fabrication of photoresponsive Janus particles (JPs) composed of an epoxy-based azo polymer and poly(methyl methacrylate) (PMMA). Two representative azo polymers, where BP-AZ-CN bears cyano groups as electron-withdrawing substituents on azobenzene moieties and BP-AZ-CA bears carboxyl groups as the electron-withdrawing substituents, were adopted for the investigation. The nano-scaled JPs with a narrow size distribution and different ratios of the azo polymers to PMMA were fabricated through self-assembly in solutions and dispersions...
October 5, 2016: Chemistry, An Asian Journal
Melanie Hammerich, Christian Schütt, Cosima Stähler, Pascal Lentes, Fynn Röhricht, Ronja Höppner, Rainer Herges
Diazocines, bridged azobenzenes, exhibit superior photophysical properties compared to parent azobenzenes such as high switching efficiencies, quantum yields, and particularly switching wavelengths in the visible range. Synthesis, however, proceeds with low yields, and derivatives are difficult to prepare. We now present two heterodiazocines which are easier to synthesize, and the general procedures should also provide facile access to derivatives. Moreover, both compounds can be switched with light in the far-red (650 nm)...
October 4, 2016: Journal of the American Chemical Society
Thomas Moldt, Daniel Przyrembel, Michael Schulze, Wibke Bronsch, Larissa Boie, Daniel Brete, Cornelius Gahl, Rafal Klajn, Petra Tegeder, Martin Weinelt
Azobenzene-alkanethiols in self-assembled monolayers (SAMs) on Au(111) exhibit reversible trans-cis photoisomerization when diluted with alkanethiol spacers. Using these mixed SAMs, we show switching of the linear optical and second harmonic response. The effective switching of these surface optical properties relies on a reasonably large cross section and a high photoisomerization yield as well as a long lifetime of the metastable cis isomer. We quantified the switching process by X-ray absorption spectroscopy...
September 28, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Danyang Liu, Sijia Wang, Shouhong Xu, Honglai Liu
Azobenzene-contained glycolipids GlyAzoCns, newly structured azobenzene derivatives, which have an azobenzene moiety between the galactosyl and carbon chains of various sizes, have been synthesized. The GlyAzoCns undergo reversible photo-induced isomerization in both ethanol solution (free state) and liposomal bilayer (restricted state) upon irradiation with UV and Vis-light alternately. The drug release of Liposome@Gly induced by isomerization was found to be an instantaneous behavior. The photo-induced control of DOX release from liposome was investigated in various modes...
September 26, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Ivan Tochitsky, Zachary Helft, Victor Meseguer, Russell B Fletcher, Kirstan A Vessey, Michael Telias, Bristol Denlinger, Jonatan Malis, Erica L Fletcher, Richard H Kramer
Azobenzene photoswitches confer light sensitivity onto retinal ganglion cells (RGCs) in blind mice, making these compounds promising candidates as vision-restoring drugs in humans with degenerative blindness. Remarkably, photosensitization manifests only in animals with photoreceptor degeneration and is absent from those with intact rods and cones. Here we show that P2X receptors mediate the entry of photoswitches into RGCs, where they associate with voltage-gated ion channels, enabling light to control action-potential firing...
October 5, 2016: Neuron
Randy L Lawrence, Billy Scola, Yue Li, Chang-Keun Lim, Yang Liu, Paras N Prasad, Mark T Swihart, Marc R Knecht
We introduce here a concept of remote photoinitiated reconfiguration of ligands adsorbed onto a nanocatalyst surface to enable reversible modulation of the catalytic activity. This is demonstrated by using peptide-ligand-capped Au nanoparticles with a photoswitchable azobenzene unit integrated into the biomolecular ligand. Optical switching of the azobenzene isomerization state drives rearrangement of the ligand layer, substantially changing the accessibility and subsequent catalytic activity of the underlying metal surface...
October 3, 2016: ACS Nano
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